Vapor oxygen recondenser



March 4, 1952 R CARTER 2,587,820

VAPOR OXYGEN RECONDENSER Filed May 16, 1947 J l/ l, L\ 02 wapo@ i REco/voE/vsea 02 VAPOR FROM Patented Mar. 4, 1952 VAPOR OXYGEN RECONDENSERu Lionel It. Cartier, OFallon, Ill.; Eliie Mae Cartier and Norman J. Gundlach, executors of said Lionel R. Cartier, deceased, assignors to Independent Engineering Company, Inc., OFallon, Ill., a corporation of Illinois Application May 16, 1947, Serial No. 748,413

3 Claims.

. VThe present invention relates to a vapor oxygen recondenser, or to a recondenser for a rectier system operating comparably to a system for production of oxygen from air. More particularly. it relates to a recondenser for use in connection with oxygen columns of the presently existing type, which recondenser is adapted to take vapor oxygen from the column and recondense the same at least in part, employing as a refrigerating agent vapor nitrogen from` another part of the column which is vaporized and expanded in heat transfer relationship to the oxygen, so that the nitrogen absorbs heat from the oxygen and lquenes at least a part of the latter.

It is an object of the invention to provide an oxygen recondenser of this type which may be added to existing columns. A further object of the invention is to provide a recondenser of this type that will operate with minimum heat loss. A specific object is to provide such a recondenser superposed onto the top of a column of known style, whereby to receive cold nitrogen vapor immediately from the upper rectifying chamber, and into which vapor oxygen from said chamber may be conducted for at least partial liquefaction.

In the drawing:

Fig. 1 is a diagrammatic view of the apparatus of the present invention applied to an oxygen column; and 'l Fig. 2 is a section on the line 2 2 of Fig. 1.

This invention will be described in connection l with the production of oxygen from air. It will be understood, however, that its principles and apparatus are equally applicable to the production of other liquid products of systems that are similar to oxygen producing systems, in fractionating, out of a fluid mixture, one gas having one boiling point from other gas having a different boiling point.

In the drawing, there is a, column, generally indicated at I0. This column has a lower separating chamber II, above which is a lower condenser, generally indicated at I2. Above the lower condenser I2, there is an upper separating chamber I3. Above this, in the present invention. there is mounted an additional condenser I4, that comprises a heat exchanger having separate passes in separated, heat-exchange relationship to each other.

Associated with the column in the present explanation is a sub-cooler, generally designated at I 8. This sub-cooler improves the efficiency of the system, but is not essential to it.

The column, in the manufacture of oxygen, is conventionally associated with sources of air.

( Cl. GZWIZZ) 80 p. s. i. and 154 C. as it enters the upper expanded and delivered to the chamber I I.

coil 2|. Such values are typical of known sys.- tems.`

Additionally, there is an inlet line 22 from the liqueiier which delivers air under pressure to a coil 23 within the chamber II. From the other end of this coil, this air is carried by a pipe 24 to a rst expansion valve 25, at which point it is cally, the air in the pipe 22 may be at 600 p. s. i. and 130-C. As it passes through the coil 23, in heat transfer relation with the interior of the chamber II, it is cooled to about 177 C. At the expansion valve 25, it is reduced in pressure to the pressure of the chamber II, suggested to be 30 p. s. i., whereupon a portion of the liquefied air flashes into vapor, reducing the temperature of the remainder to or toward the boiling point of the air at the pressure within the chamber II.

Conventionally, the chamber I I above the coils 2l and 23 has liquid receiving trays such as illustrated at 2l. Above these is a liquid shelf 28 below the condenser I2 and adapted to catch a part of the liquid therefrom.

As the air expands from the valve 25, lowering the temperature of at least part of it, a partial separation occurs, in which a mixture of nitrogen and oxygen rises as a gas, and a mixture oi' oxygen and nitrogen as a liquid descends onto and through the trays. Vapor from the upper coil 2| rises to bubble through the trays, and is itself cooled by the descending liquid to a temperature at which separation occurs. There is thus produced in a sump 29 at the bottom of the chamber II a liquid oxygen-nitrogen mixture, called crude oxygen, and containing in the neighborhood of 50% oxygen. It is generally designated as a liquid rich in oxygen. Its temperature may be about 188 C.

As nitrogen has a lower boiling point than exygen, it will remain at the temperatures indicated, to a large extent a vapor, which rises into the condenser I2. Here it is in heat transfer .relation with liquid oxygen of the upper column,

and is cooled and partly liquefied, this liquid gen at such pressure.

sure. The liquid separated in the condenser I2, in its lower pass, descends, partly mixing with that on the trays, and acting as a reiux liquid.

It partly collects on the shelf 28. The liquid on the shelf is largely nitrogen, and is generally designated as a liquid rich in nitrogen owing to the relatively greater percentage of nitrogen in it than in the liquid in the sump 29.

Liquid from the sump 29, which may be at 80 p. s. i. and 188 C., is withdrawn through a pipe 30, connected to the sub-cooler I6. From the sub-cooler I6, the crude oxygen, at a somewhat lower temperature, passes out in a line 3l leading to an expansion valve 32 that discharges into the upper chamber I3. At this point, it expands and cools. If the upper chamber I3 is at a typical 6 p. s. i., the'fluid from the expansion valve 32 may reduce in temperature to 191 C., or lower, but above the boiling point of nitrogen and labove the boiling point of the liquid rich in nitrogen, there being enough flashing of liquid into gas 4to produce such temperature reduction. As a re- `,II 'is expanded into the upper chamber I3. De-

sirably,.bu `t not necessarily, it is passed through jthe sub-,cooler I6 before being expanded. To aecomplish'the foregoing, a pipe 55 is connected innto the lower chamber to conduct this liouid from thechamber II. Y J6. A A pipe 55 leads from the cooler to an expan- This pipe leads into the cooler sion valve 5l, that discharges into the upper part of the chamber I3.. As this liquid is largely nitrogen, it has a low boiling Ypoint, and its expansion to `6 p. s. i. will cause it to lower in temp'erature toward or to the boiling point of nitro- For example, this, nitrogen will approach 194 C. in the upper part of the chamber I3. It will liquefy oxygen vapor in such part, and cause the oxygen thus to separate .out and descend through the trays.

Theliquid oxygen in-highly purified state decends into the condenser I2 around the tubes. It may be at theboiling point of oxygen for the pressure existing in the condenser, such as 182 f C. It may be drawn off through the valved pipe 35. Vapor oxygen rising through the trays is liquefied by contact with the cold oxygen liquid and with the cold nitrogen produced at the expansion valve 51. Y

Above, the liquid oxygen in the condenser. there is Vapor oxygen. Such vapor Vas remains unliquefled may be drawn off and used or stored as vapor oxygen. However, for many reasons, it is Y j desirable to reduce as much vapor oxygen to liquid as is possible.

45. valved at 46. leads into one pass of an upper chamber o f a recondenser I4. From'this recon- I ceives the very cold nitrogen rising from the chamber II, which transfers heat from the oxygen vapor, and then discharges through a pipe 6I). From this pipe, it may flow through one pass of the unit I6, and thence into a nitrogen discharge line 6I, that may lead, if desired, into other heat exchangers or apparatus.

When the product from the column is required to be vapor, the valves 46 and 54 are closed. All vapor then flows past the valve 43, by way of the pipe 42 to the discharge line 44 yfor suitable disposition at point of use or storage.

To recondense the Vapor oxygen, the valve 43 is closed and the Valves 46 and 54 are opened, forcing all of the vapor oxygen from the line 40 through the line 45 into one pass of the upper chamber of the recondenser I4. I'Ihereina portion of the vapor oxygen is liqueed by heat exchange with the cold nitrogen rising through the other pass of the recondenser chamber. The remaining uncondensed oxygen vapor passes out the line 53, past the valve 54, and into the vapor oxygen dischargeline 44. Y

As this nitrogen vapor through the recondenser I4 is below the boiling temperature of oxygen, and has had little opportunity to become warmed by extraneousrheat, it absorbs heat from theV oxygen vapor, and causes a substantial part 4thereof to liqueiy and collect in the bottom ov the upper condenser I4. This may be drawn 0E by the pipe 48, valved at 59. Y

, The foregoing system takes vapor oxygen at a point where it is substantially free of nitrogen. The pipe 4I! draws o from the top of the condenser, near the liquid level of the oxygen in the condenser, and at a level, with respect to the chamber I3, below that at which nitrogen in substantial ratio is found. This vapor is then transferred to the top of the column, into heat transfer relationship with the expanded vapor nitrogen atY its coldest range of temperatures, and where the nitrogen has had minimum opportunity to gain heat beyond that absorbed vfrom the vapors `and liquid in the chamber i 3. i

The present arrangement saves space, and is readily added to existing c oluinns. It has "been Yfound to-increase the liquid oxygen production substantially, by liquefying as much as V3O-35% -of the Vapor oxygen.

chamber immediately above the liquid level,` an 4oxygen discharge outlet'oonnected to the rdrawofr, a heat exchanger superposed on the chamber, having a first pass directly open to the ychamber to receive the cold nitrogen vapor, `and having 4a nitrogen outlet at its other end, and having a second pass ,in heat transfer relationship to the `rst pass, a connection betweenvthe second'pass and the vapor oxygen vvvspaceabove .the liquid in the chamber, an oppositeV connection from the second pass'to the oxygen .discharge outlet, means to regulate the amounts of oxygen vapor sent directly to the oxygen discharge outlet and to the second pass', and means to withdrawliquid oxygen from the heat exchanger'.y

2. In an oxygen column, an upper chamber having an inlet for reception of an expanding liquid rich in oxygen and another inlet for reception of an expanding liquid rich in nitrogen, a collector for liquid oxygen at the bottom of the chamber, an outlet adjacent to but above the bottom of the chamber for withdrawal of pure vapor oxygen immediately above the liquid oxygen, a heat-exchange device at the top of the chamber above the nitrogen inlet, the heat exchanger having two passes in heat-exchange relationship, one being a nitrogen gas pass directly open to the chamber and forming a continuation thereof, a nitrogen outlet above the heat exchanger. to cause nitrogen to rise in the upper chamber, pass through the nitrogen pass of the heat exchanger, and act in heat transfer relationship to the other pass, and means connecting the vapor oxygen outlet into the other pass, a liquid oxygen outlet from said oxygen pass of the heat exchanger, and a vapor oxygen outlet from said pass, whereby said vapor oxygen may be at least partially liquefied by heat transfer into the vapor nitrogen as the latter rises directly from the upper chamber.

3. In an air rectification column for liquefying a rst gas out of air containing at least one other gas herein designated a second gas, the first gas having a higher boiling point than the second gas: an upper chamber having an inlet for reception of an expanding liquid rich in the first gas and another inlet for reception of an expanding liquid rich in the second gas, a collector for liqueed rst gas at the bottom of the chamber,

an outlet adjacent to but above the bottom of the chamber for withdrawal of pure first gas immediately above the liqueed rst gas, a heat exchange device at the top of the chamber above the second gas inlet, the heat exchanger having two passes in heat exchange relationship, one being a second gas pass directly open to the chamber and forming a continuation. thereof, a second gas outlet above the heat exchanger' to cause the second gas to rise in the upper chamber, pass through the second gas pass of the heat exchanger and act in heat transfer relationship to the other pass, and means connecting the first gas vapor outlet into the other pass, a liquid rst gas outlet from said first gas pass of the heat exchanger, and a vapor first gas outlet from said pass, whereby said rst gas may be at least partially liquefied by heat transfer into the first gas as the latter rises directly from the upper chamber.

LIONEL R. CARTIER.

REFERENCES CITED The following references are of record in the le `of this patent:

UNITED STATES PATENTS Number Name Date 1,963,809 Schuftan June 19, 1934 2,051,576 Schlitt Aug. 18, 1936 2,406,003 Dennis Aug. 20, 1946 2,409,458 Van Nuys Oct. 15, 1946 

1. AN APPARATUS FOR PRODUCING LIQUID OXYGEN, INCLUDING A COLUMN HAVING AN UPPER CHAMBER IN THE BOTTOM OF WHICH LIQUID OXYGEN IS PRODUCED WITH VAPOR OXYGEN IMMEDIATELY THEREABOVE, AND IN THE TOP OF WHICH VAPOR NITROGEN IS PRODUCED AT TEMPERATURES BELOW THE BOILING POINT OXYGEN AN OXYGEN VAPOR DRAW-OFF CONNECTED INTO SAID CHAMBER IMMEDIATELY ABOVE THE LIQUID LEVEL, AN OXYGEN DISCHARGE OUTLET CONNECTED TO THE DRAWOFF, A HEAT EXCHANGER SUPERPOSED ON THE CHAMBER, HAVING A FIRST PASS DIRECTLY OPEN TO THE CHAMBER TO RECEIVE THE COLD NITROGEN VAPOR, AND HAVING A NITROGEM OUTLET AT ITS OTHER END, AND HAVING A SECOND PASS IN HEAT TRANSFER RELATIONSHIP TO THE FIRST PASS, A CONNECTION BETWEEN THE SECOND PASS AND THE VAPOR OXYGEN SPACE ABOVE THE LIQUID IN THE CANMBER, AN OPPOSITE CONNECTION FROM THE SECOND PASS TO THE OXYGEN DISCHARGE OUTLET, MEANS TO REGULATE THE AMOUNTS OF OXYGEN VAPOR SENT DI- 